1. Field of the Invention
The present invention relates to a light stabilizer used for stabilizing light source operation of a printer such as a laser printer and a copier, a light stabilization method, and a printer using the same.
2. Description of the Related Art
In the past, in such a printer, a laser diode as a light source is mounted on an encapsulated type package, for example, as illustrated in FIG. 13. In such a light source module 100, a heat sink 102 is arranged on a disc stem 101. A laser diode 106 is mounted on the heat sink 102 with a sub-mount 105 in between, and is sealed with a sealing cap 107. Laser light from the laser diode 106 is outputted outside through a window glass 108 provided on the front face of the sealing cap 107. Inside of the sealing cap 107 is filled with gas having lower dew-point temperature than temperature in external environment.
In the light source module 100, for airtight sealing, the sealing cap 107 and the stem 101 are fixed with each other by electric welding or brazing, and the sealing cap 107 and the window glass 108 are fixed with each other by low melting point glass or brazing. Similarly, lead pins 103a, 103b, and 103c are fixed to the stem 101 by low melting point glass, and thereby sealing and electric insulation are made. In addition, for a metal section of the stem 101 and the sealing cap 107, surface treatment is provided for facilitating joint of brazing or low melting point glass. For the window glass 108, plating treatment for brazing is provided.
Further, in the encapsulated type light source module 100, in the assembly step, the stem 101 on which the laser diode 106 is mounted is left in the gaseous atmosphere in which dew point is managed for a certain time. After moisture of the surface of the stem is extracted, the sealing cap 107 is electrically welded to the stem 101. Finally, presence of leakage is individually inspected by an apparatus such as a helium leakage checker. As described above, the light source module 100 in which the encapsulated type package is used should be manufactured through many steps. Thus, there has been a disadvantage that it costs a lot for assembly and inspection, and a major assembly equipment and a major inspection apparatus are necessitated.
Meanwhile, in the case where a printer is started in low temperature environment, there is a disadvantage that when the power source is turned on, temperature in the printer is increased, leading to dew condensation in the vicinity of the laser diode and the laser device itself. Further, in the case of printing, in some cases, if the inside of the light source module in which the laser device is heated is contacted with cool external air, dew condensation is shown in the window glass. Accordingly, in the past, the expensive light source module that is airtight-sealed as described above has been used.
In order to prevent dew condensation in such low temperature environment, a method of controlling temperature of a laser device by using a peltiert device has been proposed (Japanese Unexamined Patent Application Publication No. 61-79285). That is, in the case where the module is exposed at lower temperature than dew point temperature, the laser device is heated up to the degree equal to or higher than the dew point temperature by the peltiert device. Thereby, without relation to the atmosphere temperature and humidity, dew condensation of the window glass is able to be prevented.